A flaw was found in lighttpd version 1.4.31 that could be exploited by a remote user to cause a denial of service condition in lighttpd. A client could send a malformed Connection header to lighttpd (such as "Connection: TE,,Keep-Alive"), which would cause lighttpd to enter an endless loop, detecting an empty token but not incrementing the current string position, causing it to continually read ',' over and over.

This flaw was introduced in 1.4.31 [1] when an "invalid read" bug was fixed [2].